Since 1990, HydroTher Hot Tubs have been the #1 choice of architects, consultants, designers and facility operators for commercial aquatic applications.
By Colin Taylor, B.Sc.
Even in the cold, hot tub water chemistry should be kept at the same general levels as any other season.
For many homeowners, the decision to close their hot tub for the season is not as automatic as it is for most pool owners. Just because the leaves change colours and the temperature drops, it does not mean the hot tub has to be winterized, putting an end to the warm-water therapy season (at least for a few months).
The customer’s choice whether or not to winterize their hot tub is personal and is based on many things. For instance, some may elect to close their hot tub based on whether they are going to be home for the winter, if their hot tub is not located within an enclosure (e.g. gazebo), or if it is not easily accessible via a covered walkway.
However, those customers who want to use their hot tub after the snow has fallen should be provided with the following tips to prevent cracks from developing during the winter deep freeze. These problems can occur when stagnant water expands and contracts in and around the plumbing, jets, and other components after it freezes and subsequently thaws.
This article will help retailers and service professionals explain to customers the proper way to maintain water in their hot tub during the winter—as well as how to close it properly if they so choose. It will also provide important water care tips that should be passed on to the customer that are unique to the winter season and inclement weather.
Even in the cold, hot tub water chemistry should be kept at the same general levels as any other season to ensure the homeowner has an enjoyable bathing experience. When using a test strip, the following readings should be targeted:
pH 7.2 to 7.6
chlorine 3 to 5 parts per million (ppm) or bromine 4 to 6 ppm
alkalinity 80 to 120 ppm
hardness 100 to 250 ppm
It is also a good idea for the customer to add a water conditioner that buffers pH and alkalinity values from week to week, as it can make water care easier in the winter. Keep in mind, sanitizer levels will fall quickly each time they use their hot tub; therefore, the customer should be advised to add chlorine or bromine regularly.
It should also be recommended they use a non-chlorine monopersulfate shock oxidizer every time they exit the hot tub. This will help to neutralize organics such as body oils, as well as prevent unwanted proliferation. Further, it allows the sanitizer to last longer and work more efficiently.
Customers should also pay closer attention to the water temperature in the winter. One way they can do this is to set their hot tub to auto-heat, or other equivalent setting, which will allow it to run for at least 15 minutes every hour. If the client’s hot tub is equipped with a 24-hour circulation pump, this is a moot point because the water is constantly circulating.
Homeowners should periodically check the water and continue to add a sanitizer during the winter when they are not using their hot tub.
The practice of keeping the water temperature consistent is also a more energy-efficient way for them to operate their hot tub in the winter, as opposed to turning the temperature down and then back up again. As a side note, in the event of a power outage, it will take three to five days for a hot tub heated to 40 C (104 F) to completely freeze.
There are several external considerations the customer should be aware of when using their hot tub in frigid temperatures:
Use a floating thermal hot tub blanket to reduce evaporation.
Protect the hardcover using a vinyl-cover spray.
Clear snow off the hot tub cover before lifting it. This will prevent snow from falling into the hot tub and messing up the water chemistry.
If the hot tub cabinet is made of wood, apply a weatherproof sealer or linseed oil to prevent moisture absorption and freeze-thaw damage.
For customers who know they are not going to brave the elements and head outside for a soak should be told to keep their water heated, but a much lower temperature than what they would normally set it for bathing.
When winterizing the hot tub, open the cabinet and loosen/unscrew all visible quick disconnect fittings on both sides of the heater and pump(s) to allow water to drain during the winter.
Most people enjoy their hot tub water at plus/minus 39 C (102 F); however, for customers who have decided not to use their hot tub, they can save energy by turning the water temperature down to plus/minus 15 C (60 F), while also ensuring the circulation pump is operating.
Before the customer takes their last soak of the season, tell them to adjust (balance) the water’s pH and alkalinity. Since the water will not be used, a concentrated shock treatment, along with a winter algaecide, should also be administered.
To ensure the plumbing remains clear, the hot tub owner should periodically run the jet pumps to circulate the water. The latent heat in the hot tub will also maintain a safe temperature to prevent freezing. If the customer’s hot tub has a freeze protection setting, or can be set to filter the water more often, this will do the trick. In many hot tubs, a ‘standard’ setting or ‘F3’ filtration option should keep the water circulating, while most modern units have a built-in sensor that turns the heater on when temperatures dip below freezing.
Even though the hot tub is not being used, evaporation remains an issue—especially in the cold. If the water level drops below the highest jet, it could cause the hot tub to stop working.
In addition to evaporation, maintaining proper water chemistry should still be stressed. While the homeowner’s regular water maintenance routine should wane a bit, as organics are not being introduced to the water, retailers and service professionals should advise customers to periodically check the water and continue to add a sanitizer (e.g. chlorine)—at the very least.
The goal is to keep the water circulated and oxidized. Using a water conditioner will help prevent spikes in pH, which will allow the water to last longer, while total dissolved solids (TDS) will be kept to a minimum. In the spring, the customer can decide whether to drain and refill their hot tub.
Improper winterization methods are the main cause of damage to hot tubs installed in cold-climate regions. Should a hot tub freeze in the winter, the damage that can occur can be quite costly for the consumer to repair.
While some homeowners will attempt to close their hot tub themselves, many prefer to leave this task to their local retailer or service professional. To winterize a hot tub properly, a service professional should follow these steps:
Turn off the power to the unit (at the breaker box and the main circuit on the home panel).
Attach a garden hose to the spout on the bottom of the hot tub and drain the water. The drain should be kept open all winter. A submersible pump or shop vac can be used to help remove any remaining water in the foot well and plumbing lines. Towels can be left in the foot well to soak up lingering water.
Remove the filter(s) and dry the filter compartment. Instruct the customer to store the filter(s) in a dry location until spring.
Access the hot tub’s equipment behind the cabinet and loosen/unscrew all visible quick disconnect fittings on both sides of the heater and pump(s). Leave these fittings disconnected to allow water to come out all winter. Remove any other drain plugs to prevent cracking.
Blow out any residual water from the jet piping using a reversible shop vac or air compressor to clear each jet. If the hot tub has topside air controls, close them.
Do not use anti-freeze in an acrylic hot tub. Anti-freeze is only necessary if water is left in the plumbing; however, there are better alternatives (see ‘Preventing the hot tub from freezing’ above). Anti-freeze can be problematic to remove before opening the hot tub in spring.
Completely cover the hot tub—including the cabinets. Keep in mind, water can still pass through the middle seam of the hardcover, as it is not waterproof. Therefore, to prevent this from happening, an additional winter cover or large marine-grade tarp should be placed on top, draping it over the edge down to the ground. The cover should be cinched tightly around the cabinetry at the base using a cable, rope, or bungee. Then, secure the extra cover or tarp with bricks or stakes. A winter cover that encompasses the hot tub also prevents animals from seeking shelter in the unit.
To ensure there is no lingering buildup in the plumbing, the hot tub should be drained and refilled in the spring.
With methodical guidance from a retailer or service professional, those homeowners who take care of their hot tubs over the course of the winter will be happy come spring.
However, a retailer’s assistance does not stop here. Customers should be advised to start the season by topping up their hot tub and performing a plumbing line purge. After purging, the hot tub shell should be cleaned, but make sure the customer uses a cleanser that will not damage the acrylic surface.
Finally, to ensure there is no lingering buildup in the plumbing, the hot tub should be drained and refilled. This step will help remove the winter water and help clean out the maze of plumbing lines that run beneath the unit.
At the start of every season, retailers should remind their customers what water values they should maintain, which are essentially the same year-round. Whichever way the customer chooses to use—or not use—their hot tub, following the procedures outlined in this article will ensure they enjoy a fresh start-up in the spring.
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